<!--Từ sau PHP 5.3 dùng const thay thế cho define() tốt hơn.
Tham khảo  : http://stackoverflow.com/questions/2447791/define-vs-const/3193704#3193704-->
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<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>PHP Constants</title>
</head>
<body>
<h1>PHP Constants</h1>
<div>
    <h3>Case-sensitive constant</h3>
    <?php
    define("GREETING", "Welcome to W3Schools.com!");
    echo(GREETING);
    ?>
</div>

<div>
    <h3>Case-insensitive constant</h3>
    <?php
    define("GREETING1", "Welcome to W3Schools.com!",true);
    echo(greeting1);
    ?>
</div>

<div>
    <h3>New Constant for PHP 5.3</h3>
    <?php
    const abc = "LALA";
    echo(abc);
    ?>
</div>
</body>
</html>